Wittig Reactions in Water Media Employing Stabilized Ylides with Aldehydes. Synthesis of α,β-Unsaturated Esters from Mixing Aldehydes, α-Bromoesters, and Ph<sub>3</sub>P in Aqueous NaHCO<sub>3</sub>
作者:Amer El-Batta、Changchun Jiang、Wen Zhao、Robert Anness、Andrew L. Cooksy、Mikael Bergdahl
DOI:10.1021/jo070665k
日期:2007.7.1
range of stabilized ylides and aldehydes. Despite sometimes poor solubility of the reactants, good chemical yields normally ranging from 80 to 98% and high E-selectivities (up to 99%) are achieved, and the rate of the reactions in water is unexpectedly accelerated. The efficiency of water as a medium in the Wittig reaction is compared to conventional organic solvents ranging from carbon tetrachloride
Pd(OAc)<sub>2</sub>-Catalyzed Oxidative Coupling Reaction of Benzenes with Olefins in the Presence of Molybdovanadophosphoric Acid under Atmospheric Dioxygen and Air
作者:Masayuki Tani、Satoshi Sakaguchi、Yasutaka Ishii
DOI:10.1021/jo035568f
日期:2004.2.1
The direct oxidativecouplingreaction of benzenes with alkenes bearing an electron-withdrawing group was successfully achieved by the use of Pd(OAc)2/molybdovanadophosphoric acid (HPMoV) as the key catalyst under O2 or air atmosphere. Thus, the reaction of benzene with ethyl acrylate under air (1 atm) assisted by Pd(OAc)2/HPMoV afforded ethyl cinnamate as a major product in satisfactory yield (74%)
SO good. An efficient PdII catalyzed C−Holefination of thiophenes has been developed using an easily accessible bidentate S,O‐ligand. The catalytic system promotes the C‐2 olefination in a wide range of thiophenes including 3‐substituted thiophenes, under mild conditions.
Intramolecular Mizoroki–Heck Reaction of 2-Thiosubstituted Acrylates for the Synthesis of 3-Substituted Benzo[b]thiophene-2-carboxylates
作者:Young-Dae Gong、Se Kwak、Su-Jeong Lim、Hyun-Jeong Yoo、Ji-Eun Ha
DOI:10.1055/s-0035-1562613
日期:——
condition. 3-Substituted 2-(phenylthio)acrylates prepared from aldol condensation using titanium tetrachloride were employed to synthesize benzo[b]thiophenes. The acrylates containing aryls and alkyls generated the desired benzo[b]thiophenes in reasonable yields under the optimized Heck condition, but acrylates having heteroaryls gave the desired products in poor yields or no products under the condition
摘要 使用四氯化钛由醛醇缩合制得的3-取代的2-(苯硫基)丙烯酸酯用于合成苯并[ b ]噻吩。在优化的Heck条件下,含有芳基和烷基的丙烯酸酯以合理的收率产生了所需的苯并[ b ]噻吩,但是具有杂芳基的丙烯酸酯在该条件下收率较低或没有产物。 使用四氯化钛由醛醇缩合制得的3-取代的2-(苯硫基)丙烯酸酯用于合成苯并[ b ]噻吩。在优化的Heck条件下,含有芳基和烷基的丙烯酸酯以合理的收率产生了所需的苯并[ b ]噻吩,但是具有杂芳基的丙烯酸酯在该条件下收率较低或没有产物。
Solvent-free Wittig olefination with stabilized phosphoranes—scope and limitations
Neat mixtures of arene/hetarenecarbaldehydes, alkanals as well as alkenals with alkyl (triphenylphosphoranylidene)acetates react exothermally to furnish the corresponding alkenes. In certain cases, heating has to be provided externally. Reaction times are short and yields are generally very high. Neat mixtures of ketones and alkyl (triphenylphosphoranylidene)acetates react preferentially under microwave irradiation. The better stabilized phosphoranes do not react in the solid state with aldehydes or ketones under conventional heating, but necessitate microwave irradiation, although not all of the phosphoranes have been found to be stable under microwave irradiation at 500 W (2450 MHz).